Ticket sales are delayed. Mojang's people are talking to other people but the other people haven't told them enough yet. If that doesn't make sense, the Mojang update announcement is at MineCon: The Waiting Game

Today I’m implementing PayPal as a MineCon option, all you with failed checkouts will get the chance to try again.
I’m aiming to release a big new batch of tickets tomorrow, stay tuned. : )
Regarding MINECON tickets: I’m aiming to release the next batch (It’s a big one) Tuesday 5 pm my time (CEST). @Snusprillans@Dianthe_Bouquet It’s technically GMT+2 during summer time, and you guys are GMT +1, but I guess it’s right. : )

Like last time, there will be panels and talks, but there will also be a Creative Build Competition - https://minecraft.multiplay.co.uk/. It will be restricted to 1000 contestants but I can't wait to see what is made. The top three will get displayed at Minecon and get given special treatment

There will also be an interactive area, but no details have been given yet.